The morphology and the electronic structure of ultrathin Ni films grown on the oxygen-passivated Fe(001)-$p(1\times 1)$O surface are investigated by means of scanning tunneling microscopy and spectroscopy. We observe that oxygen efficiently floats on top of the Ni film and has an “anti-surfactant” effect on the Ni/Fe(001) interface, promoting the formation of two-layer-high islands since the first stages of growth, whereas the Ni growth on the oxygen-free Fe(001) surface proceeds in a layer-by-layer mode. Our experimental results show that the effectiveness of the oxygen surfactant action in the growth of metal thin films strongly depends on the choice of the substrate and overlayer combination.

• Received 14 May 2012

DOI:https://doi.org/10.1103/PhysRevB.86.075465